This invention relates to the provision of a clear gel antiperspirant stick containing an anti-perspirant metal salt and, in particular, containing aluminum chlorhydrate. More specifically this invention relates to providing a clear gel anti-perspirant stick which is the reaction product of a metal salt having anti-perspirant properties with the salt of an organic acid and with a hardening agent.
Formulations for stick antiperspirants fall into three main categories i.e., compressed powder sticks, gel sticks and wax sticks. Each of these categories have advantages in certain situations but each have definite disadvantages. Compressed powder sticks for example are frequently brittle and hard and leave a cosmetically unacceptable greasy or tacky residue upon application. Not infrequently, wax based formulations yield cosmetically unacceptable products due to such factors as hardness, greasiness and stickiness. An improvement in wax based compositions was developed with the advent of certain soap alcohol gel sticks which were used in various cosmetic preparations and when rubbed on the skin left a thin even residue which was not greasy or tacky. Unfortunately, while such material is satisfactory for a wide range of cosmetic compositions, the soap alcohol gels have proven to be unsatisfactory for applying metallic astringent compositions such as those including aluminum chlorhydrate. It is believed that the metallic ion component of the aluminum chloride complex is sensitive to the soap component which inactivates the ion.
The art has long searched for a solution to the problem of producing a clear gel stick incorporating metallic anti-perspirant materials. In U.S. Pat. No. 4,673,570 to Soldati there is described a gel anti-perspirant composition made up of a volatile silicone fluid, a silicone emulsifier and other ingredients. Unfortunately, the use of such silicone compounds are expensive and have not been satisfactory. In U.S. Pat. No. 4,722,835 to Schamper et. al., a gelled transparent stick is described which contains an acidic anti-perspirant active component gelled in the presence of dibenzyl monosorbitol acetal (DBMSA). It has been discovered that gel sticks made up from this formulation tend to be unstable and not suitable for products which must be shipped and stored for long periods of time. In U.S. Pat. No. 3,255,082 to Barton, a method of preparing a stable aluminum chlorhydrate alkaline metal or alkaline earth metal salt complex is described for the purpose of preparing gels. While the teachings of this patent proports to overcome the difficulties described above with respect to prior art suggestions, it has been found that consistent production of stable gels is not possible using these methods. In U.S. Pat. No. 2,876,163 to Garizio, et al., there is described a method for preparing aluminum chlorohydroxy "alcogel" by combining an aluminum chlorohydroxy complex with an alkaline compound in an alcohol solvent. Taught therein, among the alkaline compounds, is ammonium acetate. While indeed, the combination of ammonium acetate with the aluminum chlorohydroxy complex form gels, it has been discovered that the gelation time is extremely long, that gels formed thereby tend to be unstable and after a period of time break down, and hence the process is not completely satisfactory for commercial production of gelled anti-perspirant sticks.
Accordingly, there is a need for providing a stable, clear gelled antiperspirant stick and a method for making the same.